Kubernates notes 4 Types of YAML files in k8s

1. Deployment YAML

Deployment ka kaam hota hai ki pods create kare aur unka management kare (replica, rolling updates, etc.).

Example:

apiVersion: apps/v1       # Resource ka version
kind: Deployment          # Resource ka type
metadata:                 # Metadata section
  name: myapp-deployment  # Deployment ka naam
  labels:                 # Labels help karte hain resources ko group karne me
    app: myapp
spec:                     # Specification section
  replicas: 3             # Kitne pods chalane hain
  selector:               # Define karte hain ki kaunsa pod is deployment ka part hai
    matchLabels:
      app: myapp
  template:               # Pods ka template define hota hai
    metadata:
      labels:             # Har pod ka label
        app: myapp
    spec:
      containers:         # Container ka definition
      - name: myapp       # Container ka naam
        image: myapp:v1   # Kaunsa Docker image use hoga
        ports:
        - containerPort: 3000  # App ka port

Key Points:

replicas: Kitne pods deploy karne hain.
template: Pods ka template define karta hai.
selector: Ensure karta hai ki ye deployment kaunsa pod manage karega.

2. Service YAML

Service ka kaam hota hai ki pods ke upar network traffic ko manage kare.

Example:

apiVersion: v1           # Service ka version
kind: Service            # Resource ka type
metadata:
  name: myapp-service    # Service ka naam
spec:
  selector:              # Kaunse pods is service ka part hain
    app: myapp
  ports:                 # Service ke ports define karte hain
  - protocol: TCP
    port: 80             # Service ka port (external)
    targetPort: 3000     # Pod ke andar ka port
  type: LoadBalancer     # Service ka type

Key Points:

selector: Ye service kaunse pods ko target karegi.
type:
- ClusterIP (default): Sirf cluster ke andar access milega.
- NodePort: External traffic ke liye specific port open karega.
- LoadBalancer: Public-facing service ke liye.

3. ConfigMap YAML

ConfigMap ka kaam hota hai ki non-sensitive configuration ko store kare (e.g., environment variables).

Example:

apiVersion: v1
kind: ConfigMap
metadata:
  name: myapp-config     # ConfigMap ka naam
data:                    # Configurations store hoti hain yaha
  DATABASE_URL: mysql://db-user@db-host/mydb
  APP_MODE: production

Use in Deployment:

containers:
- name: myapp
  image: myapp:v1
  env:
  - name: DATABASE_URL
    valueFrom:
      configMapKeyRef:
        name: myapp-config
        key: DATABASE_URL

Key Points:

ConfigMap ko data section me store karte hain.
Deployment ke env section me isse use karte hain.

4. Secret YAML

Secret ka kaam hota hai ki sensitive data (e.g., passwords, tokens) ko securely store kare.

Example:

apiVersion: v1
kind: Secret
metadata:
  name: myapp-secret     # Secret ka naam
type: Opaque             # Default type
data:                    # Base64 encoded data
  DB_PASSWORD: bXlwYXNzd29yZA==   # "mypassword" ka Base64

Use in Deployment:

containers:
- name: myapp
  image: myapp:v1
  env:
  - name: DB_PASSWORD
    valueFrom:
      secretKeyRef:
        name: myapp-secret
        key: DB_PASSWORD

Key Points:

Secret ko Base64 me encode karte hain.
Encode karne ka command:
```
echo -n "mypassword" | base64
```

5. Ingress YAML

Ingress ka kaam hota hai ki external HTTP/HTTPS traffic ko route karna.

Example:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: myapp-ingress
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /
spec:
  rules:
  - host: myapp.example.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: myapp-service
            port:
              number: 80

Key Points:

host: Define karta hai ki kaunsa domain is ingress ko target karega.
backend: Service ka naam aur port jaha traffic route hoga.
Ingress ke liye external ingress controller chahiye hota hai (e.g., NGINX Ingress Controller).

6. Persistent Volume (PV) & Persistent Volume Claim (PVC) YAML

PV aur PVC ka kaam hota hai ki storage allocate karna.

Persistent Volume (PV) Example:

apiVersion: v1
kind: PersistentVolume
metadata:
  name: myapp-pv
spec:
  capacity:
    storage: 1Gi
  accessModes:
  - ReadWriteOnce
  hostPath:
    path: /data/myapp

Persistent Volume Claim (PVC) Example:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: myapp-pvc
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi

Use in Deployment:

containers:
- name: myapp
  image: myapp:v1
  volumeMounts:
  - mountPath: /app/data
    name: myapp-storage
volumes:
- name: myapp-storage
  persistentVolumeClaim:
    claimName: myapp-pvc

Key Points:

PV defines the actual storage.
PVC requests storage from PV.

7. Horizontal Pod Autoscaler (HPA) YAML

HPA ka kaam hota hai ki pods ka auto-scaling manage karna.

Example:

apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: myapp-hpa
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: myapp-deployment
  minReplicas: 2
  maxReplicas: 10
  metrics:
  - type: Resource
    resource:
      name: cpu
      target:
        type: Utilization
        averageUtilization: 50

Key Points:

scaleTargetRef: Kaunsa deployment scale karna hai.
minReplicas aur maxReplicas: Minimum aur maximum pods.
Metrics ke basis pe scaling hoti hai (e.g., CPU usage).

Summary

YAML file types and their purpose:

Deployment YAML: Pods create aur manage karne ke liye.
Service YAML: Pods ke upar network traffic route karne ke liye.
ConfigMap YAML: Non-sensitive configuration store karne ke liye.
Secret YAML: Sensitive data securely store karne ke liye.
Ingress YAML: External HTTP/HTTPS traffic route karne ke liye.
PV & PVC YAML: Persistent storage allocate karne ke liye.
HPA YAML: Pods ka auto-scaling manage karne ke liye.

Aur bhai, agar koi YAML samajhne me dikkat ho rahi hai, to bata!